This application claims the priority of German patent document 198 39 997, filed Sep. 2, 1998 and PCT International Patent Application No. PCT/EP99/06436, filed Sep. 1, 1999, the disclosures of which is expressly incorporated by reference herein.
The invention relates to an electronic circuit arrangement, which has a receiving component that detects an incoming physical signal, and supplies an electrical signal current in response thereto. The circuit arrangement includes a control and analysis component assigned to the receiving component, which is fed by a supply voltage, is acted upon by the electrical signal current and, on whose signal output, an electric analysis signal can be tapped. The electronic circuit arrangement can be operated in a first (operative) state, working when the supply voltage is switched on, and in a second (rest) state, resting without any power consumption when the supply voltage is switched off.
In many technical applications, receiving circuits for incoming physical signals are held in a wait state or rest state when no signals arrive which are to be analyzed. That is, for the purpose of an operating mode which consumes as little current as possible, it is advantageous for the circuit arrangement to be changed to a so-called xe2x80x9csleep modexe2x80x9d and, after a restarting of the signals to be detected, to automatically be changed back into the normal operative state. In the sleep mode, the circuit arrangement should consume as little electric power as possible.
Circuit arrangements are known, for example, for a use in optical transmission paths with optical waveguides, in which the opto-electronic receiver can be changed to a xe2x80x9csleep modexe2x80x9d. In a known embodiment, the implementation of the xe2x80x9csleep modexe2x80x9d function requires, in addition to the optical waveguide which transports the optical information to the optical receiving element, a separate electric connection for controlling the operating mode. In another known xe2x80x9csleep modexe2x80x9d circuit, which requires no additional electrical line, significantly higher switching expenditures are required, which result in an undesirably high current consumption in the xe2x80x9csleep modexe2x80x9d. In a preferred use of the circuit in a data transmission path in a motor vehicle, this is crucial because each saved cable and low current consumption in the sleep mode are important.
An electronic circuit arrangement of the above-mentioned type is disclosed in U.S. Pat. No. 5,115,236, in which a receiving part supplies an electric signal current and transmits it to an analysis unit. The analysis unit is coupled with a control device that is also acted upon by a quiescent-current detector which, among other things, comprises an operational amplifier. From the operational amplifier, an intensified signal current of the receiving part is transmitted to the control device which generates a corresponding through-connection signal for the analysis part. However, the present quiescent-current detector is constantly acted upon by the supply voltage and consumes a continuous quiescent current.
It is an object of the invention to provide an electric circuit arrangement of the above-mentioned type which, by means of simple circuit-related devices, controls a power consumption of the circuit arrangement in the rest state which is as low as possible.
This and other objects and advantages are achieved by the circuit arrangement according to the invention, in which a quiescent-current detector is connected parallel to the series connection consisting of the receiving component and the control and analysis component. In the rest state of the circuit arrangement (that is, when the supply voltage is switched off) the quiescent-current detector detects the signal current supplied by the receiving component, and controls switching-on of the circuit arrangement into the operative state in response thereto.
According to the invention, the quiescent-current detector comprises a switch that can be controlled by way of the quiescent current. It blocks in the operative state as well as in the rest state of the circuit arrangement, as long as no inherent current is present; and in the rest state, when a signal current of the receiving component is present, it supplies a control signal, as a result of which, by way of the subsequent logic, the circuit returns into the operative state.
The invention provides a circuit arrangement which can be used particularly for the application of very fast optical transmission paths with a continuous data flow in a motor vehicle. When used in a motor vehicle, it is very important to be able to operate the circuit arrangement in a sleep mode in which the receiver will still be active also in the case of a most minimal current consumption. When the physical (particularly optical) signal to be detected is restarted, it must automatically return to the normal operative state.
According to a particularly preferred embodiment of the invention, the quiescent-current detector comprises a switching transistor whose control connection is acted upon by the quiescent current; one of its electrode connections is coupled to ground, and the other is coupled to the supply voltage, by way of a high-ohmic resistor.
In another advantageous embodiment of the invention, the receiving component and the control and analysis component are formed by a hard-wired functional module with only three connections (ground, signal output and supply voltage) accessible from the outside.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.